Encyclopædia Britannica describe his playing style as "audacious and brilliant".[1] Sívori utilized his dribbling skills and favourite move of the nutmeg (playing the ball between an opposition players legs) to defeat defenders. Primarily a left footed player, Sívori had the ability to score with his left, his right and, despite his relatively short stature, his head; this would sometimes see him receiving kicks to the face.

Especially while with Juventus, he was able to utilise his vision and passing skills, working in unison with Charles and Boniperti. Because of his playing style, country of birth and at times rebellious nature on and off the field, Sívori is retroactively compared to a player who emerged after him; Diego Maradona, with some parts of the media dubbing him "the Maradona of the Sixties".[2][3][4]

Sívori was born in San Nicolás de los Arroyos, a town which falls within the Buenos Aires Province, in an Italian Argentine family. His paternal grandfather, Giulio Sivori, was an immigrant from Cavi di Lavagna, a hamlet in the province of Genoa, while his mother Carolina was of Abruzzese descent.[5][6] As a youngster Sívori became heavily interested in the game of football and by the time he reached his teens he was signed up to a side from his home province; River Plate.[7] The teenage Sívori was given a chance to break through into a squad which included players like the famed forwards Ángel Labruna and Félix Loustau who established themselves in the era of La Máquina, one of the foremost formations in football history.[8] He soon earned the nickname El Cabezón (bighead) from the fans, due to his playing style.[8]

River was able to win the Argentine Primera División in 1955, the title was confirmed when River beat local arch rival Boca Juniors 2–1 at La Bombonera, in Buenos Aires, with just one game remaining.[9] The same season River won the Copa Río de La Plata by beating Nacional from Uruguay. The following season he had similar success when River won the Argentine league title on the final day of the season; beating Rosario Central 4–0, with Sívori scoring the final goal.[10] Sívori would play his final game for River against the same team on 5 May 1957.

During the 1957–58 season, the 21-year old Sívori was signed by Italian club Juventus after being spotted by Renato Cesarini. Juventus paid 10 million pesos (the equivalent of £91,000) for the transfer, which was a world-record transfer fee for the time. Sívori's move would prove bad for River's league fortunes, in the 18 years after 1957 they were unable to win the league in Argentina.[11] However, they were able to complete their El Monumental stadium (previously nicknamed the horseshoe) by adding a fourth stand baring his name, with the money from the deal.[11]

The same season two other prominent Argentines moved to the Italian league: Antonio Angelillo (Inter) and Humberto Maschio (Bologna). The three were nicknamed The Angels with Dirty Faces by the media (an ironic reference to the then-celebrated Angels with Dirty Faces movie) on account of their typically South American colour and flair, and also The Trio of Death on account of their fearless playing style and clinical finishing.[12]

Prior to the arrival of Sívori and Welshman John Charles, Juventus had been going through somewhat of a slump. However, the duo along with experienced Juventino Giampiero Boniperti put together a formidable force and won Serie A during 1957–58. The good form continues and Sívori won two more scudetto titles (1959–60 and 1960–61) as well as two Coppa Italia's (1958–59 and 1959–60). Omar Sívori's hard work had paid off and he was named European Footballer of the Year (also known as Ballon d'or) in 1961.

The same year as his personal achievement however, "the Magical Trio" as they were known, had broken up with Boniperti's retirement and the following season John Charles moved back to Leeds United. Sívori stayed on with the Old Lady, notably scoring the only goal in a 1–0 victory against Real Madrid, making Juventus the first Italian side ever to win at the Santiago Bernabéu Stadium. Sívori did not win anymore championships or trophies with Juventus, and left after the 1964–65 season, because of a disagreement with new coach Heriberto Herrera.[13]

With Juventus, Sívori scored 167 goals in 253 appearances in all competitions,[14] remaining Juventus' fifth highest goalscorer ever as of 2011. He also holds the record for most Juventus goals in a single league game; during the 9–1 victory against Inter Milan on 10 June 1961 he scored six goals, this is also the joint record for any Serie A team shared with Silvio Piola of Pro Vercelli.

In 1965 he signed with Napoli helping them to a third place finish in the first season at the club, they also won the Coppa delle Alpi. During the 1967–68 season, Napoli's squad boasted talents along with Sívori such as Dino Zoff and José Altafini, the club took A.C. Milan all the way in the battle for the Serie A championship; Napoli eventually finished as second. Ironically, Sívori's last ever game was against Juventus, he was given a red card for kicking Erminio Favalli and was suspended for six matches.

He represented the Argentine national team eighteen times and registered nine goals.[14] The Argentine side of the time had a formidable attack with Sívori, Omar Oreste Corbatta, Osvaldo Cruz, Humberto Maschio and Antonio Angelillo. They were nicknamed the "caras sucias" which literally means "dirty faces" in Spanish; in reference to the way they played the game, like fun, dirty faced, mischievous children.

Following his move to Italy in 1957, Sívori was barred from playing for the Argentine national team by the Italian government. Thanks to his Italian ancestry, in April 1961 he made his debut for the Italian national team. In total Omar earned nine caps and scored eight goals while playing for the Italy.[14]

Sívori retired from the playing field in 1969. Although he retired to his native Argentina as a wealthy man, his love for the game meant that he decided to take up a further career as a coach; he coached River Plate, Rosario Central, Estudiantes de La Plata, Racing Club and Vélez Sarsfield. In 1970, Bobby Moore was arrested in Bogota, Colombia after a shop assistant claimed to have seen him steal a bracelet from the shop she was working in. After several days, the charges were quashed, and as Moore took a flight to Mexico, he met Sivori, who told him that the false accusation thing was frequent in Colombia.

From 1972 until 1974, Sívori took charge of the Argentine national team, he helped the club qualify for the 1974 FIFA World Cup. Sívori was the first man to call up Ubaldo Fillol for the national side, Fillol would become one of the most highly regarded keepers in Argentine history. After that he became a full-time scout for Juventus in South America.

In March 2004, he was named by Pelé as one of the top 125 greatest living footballers and honoured as part of the in FIFA 100. The following year in February 2005, Sívori died in his hometown of San Nicolás, at the age of 69 due to pancreatic cancer.

Giampiero Boniperti: "Playing alongside him was pure fun. Charles was the target man, while Omar used the space to put defenders in trouble. He used to play with socks down around his ankles, without any kind of protection, to show he wasn't scared of defenders. He had an incredible winning mentality."[18]